In situations in which a drive shaft, such as the output shaft from a gearbox, is submerged, and a seal has to be provided to prevent the ingress of the fluid in which the shaft is submerged, the life of the seal, particularly where the fluid contains abrasive particles, is short. For example, in dredge pumps working in sandy environments, the life of the seals is frequently on the order of 600 hours. The invention will be described as applied to a dredge pump, because it is particularly useful in that application, but its use is not limited to such an application.
It has been found that by the use of the seal system of this invention, the life of the seal can be extended to in excess of 2,000 hours. As will be appreciated from the description, the system of this invention requires additional equipment beyond what is ordinarily required, and therefore its utility depends upon a substantial improvement in the life of the seal beyond what has been known heretofore. As has been indicated, the system of this invention does in fact extend that life more than enough to justify the expense of the additional equipment.
One of the objects of this invention is to provide a seal system for a submerged drive shaft that provides long life under difficult conditions.
Another object is to provide such a system which utilizes standard components and is simple to install and maintain.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.